Chance Finding at WSU Lights Up Possibilities in Physics, Computing

An accidental breakthrough by Washington State University researchers might someday lead to much more powerful computers.

It began when graduate student Marianne Tarun was working with a particular kind of crystal, strontium titanate, in a WSU physics lab. The crystal has strange electrical properties, which interests engineers and computer scientists.

One day she discovered, to her surprise, that something had changed.

“Initially it was acting more or less like an insulator, like a plastic or rubber—something that resists electrical current. But a couple weeks later, it would act like a conductor,” said Matthew McCluskey, chair of WSU's Department of Physics and Astronomy.

Its ability to carry electricity had increased 400-fold, and it stayed that way, more or less permanently. So they got to work figuring out what caused this dramatic change, considering possibilities like contamination or moisture in the air. Then after almost two years, they landed on the answer.

“It turned out that the room lights shining on the sample that was left out, you know, on the bench, were changing its electrical properties,” said McCluskey.

The violet rays from the lab’s fluorescent lights had transformed the crystal, giving it a property called “persistent photoconductivity.”

The research is in its very early stages, but McCluskey says it has some tantalizing possibilities. You might be able to write information on it using light as your pen. That could someday lead to what’s called a “holographic memory” medium, meaning the data is in three dimensions instead of on the surface of a chip. McCluskey says it’s possible a cube the size of a die could eventually hold a terabyte of data—as much as more than 200 DVDs.